JPS6371702A - Feedback controller - Google Patents

Abstract

PURPOSE:To prevent hunting by providing a control mode determining reference value changing means and changing a control mode determining reference value in accordance with a control mode. CONSTITUTION:A deviation calculating means 1 calculates a deviation e(t) between a target value (r) and a process variable y(t) at a time (t) fed back from the output of a controlled system 3, and the control mode determining reference value is set in a control mode determining reference value setting part 3 by an operator. A control mode determining means 4 determines the control mode in accordance with the deviation e(t) calculated by the deviation calculating means 1 and the control mode determining reference value, and a control mode determining reference value changing means 5 changes the control mode determining reference value in accordance with the control mode determined by the control mode determining means 4. A manipulated variable operating means 6 operates a manipulated variable v(t) in accordance with the deviation e(t) calculated by the deviation calculating means 1 and the control mode determined by the control mode determining means 4, and this manipulated variable v(t) is inputted to the controlled system 2.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a feedback control device used for controlling the flow rate of a heat exchanger of an air conditioner.

BACKGROUND OF THE INVENTION Conventionally, feedback control devices of this type have often used PI control in which an integral action is added to a proportional action, or PID control in which an integral action and a differential action are added to a proportional action. When performing such control, an operator sets appropriate values for control parameters (proportional gain, integral time, differential time) while checking the response.

Problems to be Solved by the Invention However, in such conventional methods, hunting will occur if control parameters are set to make the response of the controlled object faster. There is a problem in that the response of the controlled object becomes slow when it is forced to set .

The present invention is intended to solve these problems, and aims to speed up the response of a controlled object without causing hunting.

Means for solving the problem In order to solve this problem, the present invention provides a deviation calculation means for calculating the deviation between the target value and the process variable, and a control mode determination reference value setting for setting the control mode determination reference value. Department and
control mode determining means for determining a control mode using the deviation calculated by the deviation calculating means and a control mode determining reference value; and changing the control mode determining reference value according to the control mode determined by the control mode determining means. The apparatus includes a control mode determination reference value changing means, and a manipulated variable calculation means for calculating a manipulated variable from the control mode determined by the control mode determiner and the deviation calculated by the deviation calculating means.

Effect: With this configuration, the control mode determining means changes the control mode depending on the magnitude of the deviation and changes the amount of operation input to the process, so that the response of the process becomes faster. Furthermore, since the control mode determination reference value changing means changes the control mode determination reference value according to the control mode, hunting can be prevented.

EXAMPLE An example of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is a block diagram of a feedback control device according to the present invention. In FIG. 1, the deviation calculation means 1 calculates the deviation between the target value r and the process variable 7 (t) at time t outputted from the controlled object 2 and fed back, Ct>
Calculate. In the control mode determination reference value setting section 3, an operator sets a control mode determination reference value. The control mode determining means 4 determines the control mode based on the deviation e (t) calculated by the deviation calculating means 1 and the control mode determination reference value. The control mode determination reference value changing means 5 changes the control mode determination reference value to the control mode determined by the control mode determining means 4.

The operation amount calculation means 6 calculates the deviation e calculated by the deviation calculation means 1.
(t) and the control mode determined by the control mode determining means 4, the manipulated variable v (t) is calculated.

This manipulated variable v (t) is input to the controlled object 2 . Fluctuations due to disturbance 7 are added to the process variable y (t) output by controlled object 2 .

Next, the crow motion will be explained.

FIG. 2 is a flowchart showing the control method.

In FIG. 2, in the control mode determination reference value setting section 3,
The operator selects the initial value m1 of the control mode determination reference value M.
Set. The deviation calculation means 1 calculates the deviation e (t) between the target value t and the process variable y (t) at time t using the formula (1
) is calculated as follows.

e (t)= r −y (t) ・・・・・・
・・・・・・・・・・・・・・・・・・(1) Next, the control mode determining means 4 calculates the deviation ・(
1) and the control mode determination reference value M, the control mode is determined as shown in Table 1.

Table 1 The control mode determination reference value changing means 6 uses the table 2 according to the control mode determined by the control mode determining means 4.
Change the value of the control mode determination reference value M as shown in . However, m2 is a control mode determination reference value change width, which is a constant given by the operator.

Table 2 The manipulated variable calculating means 6 determines the manipulated variable v (t) as shown in Table 3 based on the control mode and the proportional gain Kp. Here, Ti is an integral time and Td is a differential time, which are constants given by the operator.

Thereafter, the process returns to the deviation calculation means 1 and the same operation is repeated.

Effects of the Invention As described above, according to the present invention, when the absolute value of the deviation is larger than the control mode determination reference value, the control mode determining means maximizes or minimizes the manipulated variable, so that the response of the process becomes faster. Second, since the control mode determination reference value is changed depending on the control mode by the control mode determination reference value changing means, henching can be prevented and controllability can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a feedback control device according to an embodiment of the present invention, and FIG. 2 is a flowchart showing the operation of the same control device. 1... Deviation calculation means, 2... Controlled object, 3... Control mode determination reference value certification unit, 4...
. . . Control mode determination means, 6 . . . Control mode determination reference value changing means, 6 . . . Manipulated amount calculation means. Name of agent: Patent attorney Toshio Nakao and 1 other person
1 figure

Claims (1)

[Claims] a deviation calculation means for calculating a deviation between a target value and a process variable; a control mode determination reference value setting unit for setting a control mode determination reference value; and a control mode determination reference value setting unit that calculates a deviation calculated by the deviation calculation means and a control mode determination reference value. a control mode determining reference value changing means for changing a control mode determining reference value according to the control mode determined by the control mode determining means; A feedback control device comprising a manipulated variable calculating means for calculating a manipulated variable from a control mode determined by the control mode and the deviation calculated by the deviation calculating means.